The objectives of this project, The Children's Respiratory Study, are to investigate prospectively and longitudinally the relationships of a number of potential risk factors, including acute lower respiratory tract illnesses (LRIs) in childhood, to the development of subsequent chronic lung disorders. The specific aims of P3 are to: 1) assess the relationship of acute early childhood lower respiratory tract illnesses (LRIs) to the growth of lung function and the development of airway hyperreactivity and chronic obstructive airways disease during young adulthood; 2) elucidate the roles of atopy and pre-illness lung function in the development of acute LRIs, chronic respiratory symptoms, abnormal lung function, airway hyperreactivity and diagnoses; 3) study the interrelationships of genetic, immunologic, physiologic, environmental and infectious factors with the development of chronic respiratory symptoms, airway hyperreactivity and diagnoses; 4) assess the relationship of the initiation of smoking and passive smoke exposure to lung function, atopy, bronchial responsiveness, and pulmonary symptomatology and diagnoses. This study is being conducted on a population of 1246 children who were enrolled in the project at birth together with their families between 1980-1984 and who have been followed in depth since then. This renewal will focus on continued in-depth evaluation of changes in respiratory health in these children as they age. Baseline lung function, airway reactivity, immunologic status, atopic response, and smoke exposure will be assessed in the enrolled child. New studies proposed include a more detailed assessment of factors related to asthma and allergy. Components of reactivity will be assessed through bronchoprovocation with methacholine, diurnal variation in peak flows, and bronchodilation following administration with an inhaled bronchodilator. Data concerning the incidence and prevalence of symptoms of asthma and allergy in enrolled children will be related to similar symptoms in their parents and other family members using pedigree analyses. Finally, we will acquire and freeze blood future molecular genetic studies, as well as cellular immunologic studies. These studies will help us to determine prospectively and longitudinally the major factors relating to the development of chronic obstructive airways disease during childhood and young adult life, thereby allowing us to determine the best methods of preventing and/or treating such chronic diseases.